Add ability to get file extension from mimetype

Change-Id: I3da7be2a09c1506af72af85cd5acf5df27455a23
Respect context death on bitmap delivery as well.

Change-Id: Ia0b2ad8cc91ce631e73296b7956ae2df7d4e4445
Merge branch 'master' of https://github.com/koush/ion

# By Danesh M (1) and Koushik Dutta (1)
# Via Koushik Dutta
* 'master' of https://github.com/koush/ion:
  Respect context death on bitmap delivery as well.
  Add ability to get file extension from mimetype